This invention relates to a control device for use in association with the therapeutic mobilization and positioning devices of joints and in particular a control device that measures the force through the interpretation of the deformation in at least one component in the therapeutic mobilization device where the force is the force acting on the patient by the device or the force of the patient acting on the device or a combination of the forces.
The use of therapeutic mobilization devices is well known in the rehabilitation and treatment of injured joints and the surrounding soft tissue. Therapeutic mobilization devices have been used In association with continuous passive motion (CPM) control systems such that the joint is moved continuously over a predetermined path for a predetermined amount of time. An alternative protocol includes dynamic serial splinting or static serial splinting.
CPM and splinting entails moving the joint via its related limbs through a passive controlled range of motion without requiring any muscle coordination. Active motion is also beneficial to the injured joint, however muscle fatigue limits the length of time the patient can maintain motion or a position, therefore a device that provides continuous passive motion to the joint or progressive splinting is essential to maximize rehabilitation results. Numerous studies have proven the clinical efficacy of CPM to accelerate healing and maintain range of motion. Static Progressive Splinting (SPS) and Dynamic Splinting (DS) are accepted and effective treatment modalities for the management and modelling of soft tissue surrounding articulations. Both SPS and DS have been proven efficacious and are supported by clinical studies. CPM, SPS and DS are integral components of a successful therapy protocol.
However, none of the prior art devices show a device that automates a progressive stretch and relaxation protocol. That is none of the control systems can be adapted to progressive splinting of a patient so as to manipulate their limb to its end range of motion and hold in that position. After the patient relaxes and the soft tissue has stretched the patient can continue in the same direction of travel to achieve greater range of motion (ROM). Previously this was done with static or dynamic splints.
A control system is adapted for use in association with a therapeutic motion and splinting device. The therapeutic device has at least one component that is monitored. The system comprises the steps of defining a first maximum limit of range of motion in a first direction for the device; defining a second maximum limit of range of motion in a second direction for the device; defining a maximum reverse on load for the device; monitoring a reverse on load on the at least one component of the device including monitoring the deformation of the at least one component and interpreting the load created between the patient and the at least one component; first moving the device in the first direction of travel to a first position defined by one of the first maximum limit and the maximum reverse on load; second moving the device in the second direction of travel to a second position defined by one of the second maximum limit and the maximum reverse on load; and repeating the first and second moving steps.
In another aspect of the invention there is provided a strain gauge chassis for use in a control system for a therapeutic motion device. The strain gauge comprises a chassis and at least a first pair of strain gauges. The chassis is adapted to be attached to at least one component of the therapeutic motion device. The chassis has a base, a top portion, and first and second spaced apart side walls extending therebetween. The first pair of strain gauges are attached to opposing sides of the first side wall of the chassis and define a first bridge whereby the reverse on load of the at least one component of the therapeutic motion device is determined by monitoring the strain gauges and determining the deformation of the component and interpreting the load created between the patient and the component.
In a further aspect of the invention there is provided a strain gauge chassis for use in a control system for a therapeutic motion device. The strain gauge comprises at least one pair of strain gauges adapted to be attached to at least one component of the therapeutic motion device. The pair of strain gauges define a first bridge whereby the reverse on load of the at least one component is determined by monitoring the strain gauges and determining the deformation of the component and interpreting the loads created between the patient and the component.
In a typical CPM mode the range of motion (ROM) is defined and the device operates through a pre-defined range. In contrast in progressive stretch relaxation (PSR) a defined reverse on load force is applied to the limb and the device seeks the maximum range of motion. Sensitive reverse on load force monitoring throughout the range of motion is critical in providing safe and efficacious motion. PSR will progressively find the maximum range of motion in each cycle in sequential steps. PSR will rely on the patient""s natural relaxation response and the plastic properties of soft tissue surrounding the joint. In progressive splinting a patient has their limb manipulated to its end range of motion and held in that position. After the patient relaxes and the soft tissue has stretched the patient can continue in the same direction of travel to achieve greater ROM. The sensitive strain gauges in the device will be able to monitor the reverse on load (ROL) force and relaxation response of the patient and soft tissue and continue in the direction of travel. PSR will sequentially increase the load applied to the limb up to a defined maximum safe load. The device will drive the limb through its range of motion to the first sequential targeted ROL and monitor the force until it relaxes to a predefined value of the first sequential target. If the target relaxed load value is attained before the defined pause time the device increases its target sequential ROL and continues to drive the limb in the direction of travel. Once again the device monitors the ROL at the limb and waits for a relaxation response to increase the sequential target load. Once the maximum sequential target load is achieved the device repeats the cycle in the opposite direction of travel. If the target sequential load is not achieved within the pause time the device changes direction of travel and continues with the first targeted sequential load. If the patient resists motion or applies a load onto the device greater than the maximum preset ROL the device reverses direction.
The control system will allow the therapeutic device to be operated in CPM or PSR mode. In PSR mode the device""s primary operating parameter is the reverse on load (ROL). In PSR mode the maximum safe ROM is programmed to limit the absolute ROM a joint will experience. Whereby a safe and effective load is applied to the joint allowing the joint to experience its maximum range of motion each cycle. The objective of PSR is to accelerate achieving the ROM goals for the particular joint. PSR represents the microprocessor controlled electromechanical embodiment of progressive splinting. Progressing splinting is a common and efficacious therapy modality often used in conjunction with CPM.
Further features of the invention will be described or will become apparent in the course of the following detailed description.